In a large pot, sauté garlic in olive oil over medium-high heat for 30 seconds. Add chicken broth and potatoes and bring to a boil. Reduce heat to low, cover, and simmer for 25 minutes or until tender.
Purée soup in batches in a blender or food processor until smooth. Return to pot and add white pepper, salt, rosemary, and milk. Stir well until blended, warm through, and adjust seasonings. Serve hot, garnished with sprigs of fresh rosemary.
Reprinted with permission from The Glucose Revolution: The Authoritative Guide to the Glycemic Index (Marlowe & Co., 1999).